Dave, I considered and eliminated as few of your potential areas you point out possibly causing the problem.
At one point, when I was riding and the problem started to occur, I reached up and removed the ignition key. This killed the engine momentarily, and I open the gas cap. I actually left it partially opened, and reinserted the key in the ignition bringing the bike back to life, before the bike came to a stop. The surging and fuel starvation immediately returned and didn't go away. It wasn't a tank vent problem. When I stopped and removed the fuel pump assembly, I also pulled off the fuel filter. I could easily blow air through it with little resistance. I poured some fuel into it and it flowed right through. It showed no sign of being even partially plugged. I initially felt it was water in the tank from bad gas, so I added a fuel additive and cleaner on a half dozen occasions before removing the tank. When I removed the fuel pump assembly and drained the tank I fully expected to find a large puddle of water at the bottom of the tank, from one of those ancient little gas stations we had to use along the AK Highway, that stored gas all winter. NO Water or sediment was in the tank...... But, if I were you I would check the short piece fuel hose Dan used when modifying the extension to set the fuel pump down into the tank further. When I pulled the fuel pump assembly I found a large sheet of rubber, 2" by 3", at the bottom of my tank. The outside rubber layer of the fuel hose on mine was not compatible with gasoline and it peeled off and was at the bottom of the gas tank. It appeared it could be sucked up on to the bottom of strained and I initially felt it was the problem. The only other thing I did find was the fuel strainer as a possible culprit. It didn't look dirty, but it had a chalky white film on it and would not readily allow air from my mouth to pass. It was obvious how it was being deformed on the plastic support frame from the pump sucking hard and it was being pulled against the frame. I punched a bunch of holes in the strainer with a needle as a temporary fix. Since the on set of the fuel starvation and/or vapor locking problem, started to become predictable. I figured the problem was being caused by the heat combined with a partially plugged fuel strainer. My efforts didn't solve the problem. Every time I would start up a long slow climb at about 6 to 7,000 ft. elevation, and only during the hottest time of day, the bike would start acting like it was starting to vapor lock. It would surge and buck as it caught and died, caught and died, slowing to a stop. If I allowed it to sit for 20 minutes, I could often drive on without any sign of the problem, unless I started back up in elevation. I figure it was still a combination of things occurring at the same time. The partially blinded strainer resisting normal fuel flow and also the heat from the engine and road, plus the increase in elevation. All of which combined were causing the fuel to flash in the pump suction line and causing the bike to act up. You comments about a worn fuel may also be another link in the combination. Thanks for working on the puzzle. I also considered the possibility that the CPU was not properly correcting for elevation changes. That is an expensive fix. First I am going add a heat shield around the tank. The heat shield material was just delivered. The tank does get very hot. The gas cap almost becomes too hot to touch so it can't hurt. And, I am replacing the suction strainer. Actually, I have a new (used) fuel assembly being sent to me by David Jerome. Since the symptoms only develop at elevation....I guess I will need to ride back out west into the Rockies or up in to BC or run the Rendezvous 03 to test it all out.....;>) Or I could simply only ride in Florida at sea level and not do anything....:>)) John On 7/2/02 1:59 AM, "Dave Biasotti" <[EMAIL PROTECTED]> wrote: > John, > I wonder if you are on the right track? As you know, I also have a > Stelli Dan modified tank and have never experienced any fuel starvation > problems. There was never any heat shielding with the old tank and all > Dan added for my modified tank was a fiber pad on top of the > transmission case were very bottom of tank touches, but is to prevent > metal-to-metal contact, not heat shielding. Also never heard of any > similar problems, even from our guys in the hot southwest. I have been > in some hot, 100+ weather, run for hours in the past. > Have you checked/ eliminated any of the following; > - vent hose from filler neck - is is connected, not kinked or plugged up > were it exits down by the center stand with a bunch of other vent hoses. > Also, there is a check valve part way down, check that? Not allowing > the tank to vent as you draw down the fuel would exhibit the same > symptoms you are describing. > - the 94's came with a charcoal filter for trapping fuel fumes, but as I > recall you had to remove it to fit the enlarged tank. What did you do > with the connector hose? - hopefully didn't plug it off. > - the fuel filter - that black top hat mounted on the left, by the fuel > pump flange is expensive (but can be had from Zanotti's fairly > reasonable). Like any filter, it needs to be replaced about every 50,000 > miles. > - during the rally, the bike missed a few times (very imperceptible) and > started getting worse gas mileage. I added some fuel injector cleaner > and it ran noticeably better after a tankful of cleaner and mileage came > back up. Mexico gas and some of the no name, tim-buck-two, regular only > fill ups I did during the rally, I sure didn't trust. Injectors can be > fickle things. > - Lastly, your fuel pump. It could be pumping, but not meeting spec > pressure. Fuel injection systems require fairly high pressures for the > injectors to work. I had a fuel injected car several years back that > drove me crazy. It had spark, gas was pumping, but under load or > acceleration would start missing and bog. Turned out the fuel pump was > worn out and not delivering enough pressure (and it was in the gas tank- > what a job that was). > good luck, > -- > Dave Biasotti // Fremont, CA > > -----Original Message----- > From: GTS-1000 Owners List [mailto:[EMAIL PROTECTED]] On Behalf > Of John Laurenson > Sent: Saturday, June 22, 2002 2:49 PM > To: [EMAIL PROTECTED] > Subject: Re: Quiz Answer > > > Excellent point Carlton........It is one of the fixes I am considering. > > When you ride thousands of miles on a malfunctioning bike, worrying > that it may quite anytime, you have plenty of time to contemplate more > than your navel in looking for solutions. > > I think any heat shields that may have been on the tank, were removed > when it was rebuilt. It is something definitely needed and which I > will > install. > > I would warn everyone though that the strainer is a real potential > restriction on the GTS and a very real potential problem. It can > aggravate and make altitude and heat the final straw, as I found out. > > As I was topping off the gas tank in Salt Lake City, a guy in a car > walked up and we started talking about the vapor lock problem. He > owned > a Kaw and said he had to remove is lower fairing to stop a vapor > locking > problem. They talk about dry heat being tolerable out West, obviously > whoever says that has not driven a motorcycle in early afternoon on the > black asphalt interstates there...it is hot. > > When the GTS vapor locked climbing out of Salt Lake, the Highway > patrolman stopped and helped me push it a couple hundred yards to a > rest > stop to get out of the traffic. He wasn't even breathing hard and I > was > sure my lungs were going to start to bleed as I gasped for air. > Anything I can do to keep it from becoming a problem again is open for > discussion. > > hawke > > > > On 6/22/02 1:04 PM, "Rev. Baroonstein" <[EMAIL PROTECTED]> wrot > >> I wonder if a little heatshield (aluminumfoil or 'real' material) >> glued on to the bottom of the tank would help, it would reflect most >> of the heat from the engine. >> >> Carl >> >> ----- Original Message ----- >> From: "John Laurenson" <[EMAIL PROTECTED]> >> >> summer. The gas tank on the GTS is completely covered with plastic >> and doesn't cool down as effectively as an exposed metal tank would. >> Just >
